SGW Downlink Data Buffering for IoT Power Saving

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Solution Overview

Problem

Current 3GPP specifications discard downlink data packets when a device is in Power Saving Mode (PSM) or Extended long DRX, leading to inefficiencies in data delivery and increased network resource usage.

Innovation Solution

Implementing downlink data buffering in the Serving Gateway (SGW) or Gn/Gp-SGSN until the device exits the power saving state, allowing for efficient delivery of buffered data once the device reconnects, reducing unnecessary signaling and resource usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If downlink data packets are discarded when a device is in Power Saving Mode, then network resources are conserved, but data delivery efficiency deteriorates

Engineering Contradiction:

Improvenetwork resource usageVSAvoiddata delivery efficiency

Core Design Contradiction:

Loss of energyVSProductivity

Solution Approach 1:

The SGW buffers downlink data packets in advance when the UE is in PSM state, rather than discarding them. This preliminary buffering action ensures that data is preserved and ready for delivery once the UE becomes reachable, resolving the contradiction between conserving network resources and maintaining data delivery efficiency.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If downlink data is buffered until the device exits power saving state, then data delivery efficiency improves, but network signaling increases

Engineering Contradiction:

Improvedata delivery efficiencyVSAvoidnetwork signaling

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The patent extracts the data delivery function from the signaling path by buffering data at the SGW. This separation allows the SGW to independently manage buffered data without requiring continuous signaling with the MME, thereby reducing network signaling while maintaining efficient data delivery.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The SGW acts as an intermediary that buffers downlink data between the PGW and the UE. This intermediary function allows data to be preserved and forwarded efficiently when the UE becomes reachable, reducing the need for repeated signaling attempts and minimizing network signaling overhead.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the SGW continuously sends Downlink Data Notifications, then data delivery reliability improves, but network resource usage increases

Engineering Contradiction:

Improvedata delivery reliabilityVSAvoidnetwork resource usage

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

Instead of continuous DDN transmission, the system uses periodic action where the SGW buffers data and waits for the UE to become reachable. The MME sends a single DDN when the UE exits PSM, and the SGW delivers buffered data in response, eliminating the need for continuous signaling while maintaining reliable data delivery.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS10477428B2Node and method for buffering downlink data

Publication Date: 2019.11.12 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

Example embodiments presented herein are directed towards a mobility management node and SGW or Gn/Gp-SGSN, and corresponding methods therein, for downlink data buffering in a wireless communications network. Such buffering is useful when the wireless device is in a power saving state e.g. PSM or eDRX. Thus, since the downlink data is buffered, there is no longer a need for multiple Downlink Data Notifications to be sent.